You can use this Tutorial with any program that has a pencil tool
The base used for this tut is by Swiss Cheese Army.

Begin with drawing the outlines, remember that most boots are not tight
at the legs so don't follow the base outlines there.
For the sole 3 pixels space work best for medium bases.
Since this base is symmetrical I just copied and flipped the outline.

Now on to the Shading: With the darkest Outline color shade the inside
of the boot, to do this simply follow the outline.
For shading the sole just put 1-2 pixel lines on the left and right
side.
I'm gonna shade only the first boot now and then copy/paste/flip it.
Less work :p

Now continue shading ONLY the sole with a lighter tone.

With the next tone, continue shading the sole and the inside of the
boot itself, again just follow the outline, but this time add a line like
in the example.

Fill the remaining spaces with a lighter tone... it starts looking
like a boot :)

Now add some highlights with a lighter tone.
On the sole just draw some lines (with spaces between them), on the
boot itself a highlight where the lightest color is.
If you don't want the boots to be shiny you're finished with the shading
now, if you want more highlights read the next step as well ^^

For more Highlights take a lighter shade and fill the lines between
the old highlights on the sole.
Add some highlights to the top of the boots - and the shading is finished
:)
Now just copy and paste the boot, flip it and you have two of them.

Next the boots need laces.
Simply use the line tool (or pencil if you prefer) and draw some crossing
lines.
I usually don't copy/flip the laces to make it look more realistic.

Now add some eyes to the laces by putting 3 light grey pixels around
the ends, like shown in the example.

Now it's time for the last details. You can add some laces or a knot/ribbon
to the top and put some stitches on top of the resoles - and that's it!